Back ache is generally due to poor posture. Please make sure you sit erect with your shoulders pushed back and chest slight pushed out. You can use a pillow to support the lower back. Headache could be due to blood pressure or low haemoglobin which is medical reasons and must be checked by the doctor. If it is more simple like not eating week, not sleeping well, getting tired or being out in the sun a lot then all you need is to avoid the situation causing the headache.

it is normal in pregnancy... still u can consult ur doc, this might be due to vitamin D3 deficiency..